Lithium Ion Battery

Abstract

In order to overcome the problems in existing lithium ion batteries having high compactness and high-specific-surface-area negative electrodes of serious side reactions of electrolytes and high gas production, the present invention provides a lithium ion battery, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The negative electrode comprises a negative electrode material layer, the compaction density of the negative electrode material layer is greater than or equal to 1.4 g/cm3, and the negative electrode material layer comprises a negative electrode active material, and the non-aqueous electrolyte comprises a solvent, an electrolyte salt, a vinylene carbonate, a fluoroethylene carbonate, and an unsaturated phosphate represented by structural formula 1, and the electrolyte salt comprises LiPF6 and LiFSI. The lithium ion battery provided by the present invention has good cycle performance, high and low temperature storage performance, and lithium precipitation resistance.

1 . A lithium-ion battery, comprising a positive electrode, a negative electrode and a non-aqueous electrolyte,
 wherein the negative electrode comprises a negative electrode material layer with a compaction density of ≥1.4 g/cm 3 , the negative electrode material layer comprises a negative electrode active material, the non-aqueous electrolyte comprises solvent, an electrolyte salt, vinylene carbonate, fluoro ethylene carbonate and an unsaturated phosphate shown in formula 1, and the electrolyte salt comprises LiPF 6  and LiFSI,   
       
         
           
           
               
               
           
         
         wherein, R 1 , R 2  and R 3  are independently selected from a saturated hydrocarbyl, an unsaturated hydrocarbyl or a halogenated hydrocarbyl of C 1 -C 5 , and at least one of R 1 , R 2  and R 3  is the unsaturated hydrocarbyl; 
         wherein a specific surface area of the negative electrode active material is A m 2 /g, and based on a total mass of the non-aqueous electrolyte being 100%, a mass percentage of fluoro ethylene carbonate is B %, a mass percentage of the unsaturated phosphate shown in formula 1 is C %, a mass percentage of LiFSI is D %, wherein X=A/B, Y=B/C and Z=C/D, and X, Y and Z meet the following criteria: 
         0.1<X<1, 10<Y<150 and 0.01<Z<1. 
       
     
     
         2 . The lithium-ion battery according to  claim 1 , wherein X, Y and Z meet the following criteria: 0.15<X<0.5, 15<Y<100 and 0.03<Z<0.5. 
     
     
         3 . The lithium-ion battery according to  claim 1 , wherein the negative electrode further comprises a negative electrode current collector, the negative electrode material layer is coated on surfaces at both sides of the negative electrode current collector, and the negative electrode material layer coated on surfaces at both sides has a weight of ≥14 mg/cm 2 . 
     
     
         4 . The lithium-ion battery according to  claim 1 , wherein based on the total mass of the non-aqueous electrolyte being 100%, a mass percentage of vinylene carbonate is 0.1-3%, the mass percentage of fluoro ethylene carbonate is 0.1-30%, and the mass percentage of the unsaturated phosphate shown in formula 1 is 0.1-2%. 
     
     
         5 . The lithium-ion battery according to  claim 1 , wherein the electrolyte salt further comprises one or more of LiBF 4 , LiBOB, LiDFOB, LiDFOP, LiPO 2 F 2 , LiSbF 6 , LiAsF 6 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) 2 , LiC(SO 2 CF 3 ) 3  and LiN(SO 2 F) 2 ,
 wherein based on the total mass of the non-aqueous electrolyte being 100%, a mass percentage of the electrolyte salt is 0.1-15%.   
     
     
         6 . The lithium-ion battery according to  claim 1 , wherein the negative electrode active material comprises one or more of graphite, a silicon-containing material, a mesocarbon microbead and graphene. 
     
     
         7 . The lithium-ion battery according to  claim 1 , wherein based on the negative electrode active material being graphite, the specific surface area of the negative electrode active material is 0.5-2 m 2 /g,
 based on the negative electrode active material being the silicon-containing material, the specific surface area of the negative electrode active material is 2-3 m 2 /g.   
     
     
         8 . The lithium-ion battery according to  claim 1 , wherein the solvent comprises cyclic carbonate and chain carbonate,
 wherein the cyclic carbonate comprises one or more of propylene carbonate, ethylene carbonate and butene carbonate;   wherein the chain carbonate comprises one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate.   
     
     
         9 . The lithium-ion battery according to  claim 1 , wherein the non-aqueous electrolyte further comprises an auxiliary additive, wherein the auxiliary additive comprises one or more of 1,3-propanesultone, 1,4-butanes sultone, ethylene sulfate, methylene methanedisulfonate, tris(trimethylsilyl) phosphate, tris(trimethylsiloxy) borate, propene sultone, fluorobenzene and vinyl ethylenecarbonate. 
     
     
         10 . The lithium-ion battery according to  claim 1 , wherein the positive electrode comprises a positive electrode material layer, wherein the positive electrode material layer comprises a positive electrode active material comprising one or more of NCM523, NCM622, NCM811 and NCA. 
     
     
         11 . The lithium-ion battery according to  claim 9 , wherein based on the total mass of the non-aqueous electrolyte being 100%, a mass percentage of the auxiliary additive is 0.1-3%. 
     
     
         12 . The lithium-ion battery according to  claim 1 , wherein based on the total mass of the non-aqueous electrolyte being 100%, a mass percentage of vinylene carbonate is 0.5-1%, the mass percentage of fluoro ethylene carbonate is 0.1-15%, and the mass percentage of the unsaturated phosphate shown in formula 1 is 0.1-1%. 
     
     
         13 . The lithium-ion battery according to  claim 1 , wherein based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage of LiFSI is 0.1-12%.